Photoluminescence characteristics of the single-host white-light-emitting Sr3−3x/2(VO4)2:xEu (0≤x≤0.3) phosphors for LEDs

In this article, the single-host white-light-emitting Sr3−3x/2(VO4)2:xEu (0≤x≤0.3) phosphors were synthesized by solution combustion method using citric acid as a fuel. The synthesized phosphors were annealed at 850-1150 °C for 10 h. At first, the photoluminescence (PL) characteristics of the prepared Sr3−3x/2(VO4)2:xEu (0≤x≤0.3) phosphors emit bluish-green light with the maximum wavelength at 510 nm and sharp red emission at 611 nm under 360 nm excitation, due to the charge transfer transitions of VO43− and f-f transitions of Eu3+ ions, respectively. The XRD results show that as the europium concentration is increased, an additional EuVO4 secondary phase is formed, which is efficient red-emitting phosphor. On the other half, the luminescence intensity of VO43−decreases when the annealing temperature increases with emerging of the 5D0-7FJ (J=1, 2) transitions of Eu3+ due to efficient energy transfer from vanadate group to Eu3+. Thus, the Sr3−3x/2(VO4)2:xEu (0≤x≤0.3) phosphors were affected by the Eu3+ contents and annealing temperature. In addition, the optimal composition is found to be Sr2.85Eu0.1(VO4)2 at 1150 °C. Our results suggest that the Sr3−3x/2(VO4)2:xEu (0≤x≤0.3) phosphors may be good candidate for a new phosphor to convert the near-UV(ultraviolet) into visible wavelength bands.